Mild steel



United States Patent MILD STEEL No Drawing. Application May 3, 1957 Serial No. 656,749

Claims priority, application Great Britain May 4, 1956 1 Claim. (Cl. 75--124) The present invention relates to an improved mild steel.

The object of the invention is to provide a mild steel which has a greater resistance than hitherto known mild steels to oxidation in the presence of oxidising gases and 2,901,346 Patented Aug. 25, 1959 intentionally, are accepted as residuals and do not exert any undue harmful influence on the mechanical properties of the mild steel. The residuals also comprise sulphur and phosphorus which are inevitably present in small quantities, are considered undesirable and are usually limited to 0.06% by weight each, maximum.

Table 1 demonstrates how the addition of beryllium within the range specified above improves the resistance to oxidation of mild steels when subjected to the action of carbon dioxide at high temperature. In this table the figures for percentage composition are by weight and the discrepancy between 100% and the total of the individual percentages of the elements indicated represents the percentage of iron and residuals present in the mild steel. The oxidation index in Table 1 represents the gain in weight in mgs. per unit area of the mild steel after being maintained at 450 C. for 750 hours in a carbon dioxide atmosphere. Two oxidation indices are given, one relating to tests carried out in an atmosphere of dry CO and the other relating to tests carried out in an atmosphere of Wet CO (i.e. CO and steam).

Table 1 Percentage composition of the mild steel Oxidation Index 0 Mn Si Al Cu Ni Or Be Dry O01 Wet G0:

0.13 1. 2 0.11 0.1 to 0. 5 0. to 0. 50 Nil 0.10 Nil 9.. 00 5. 0.15 1. 2 0.11 0.1 to 0. 5 0. 25 to 0. 50 Nil 0.10 0.020 5. 15 4. 05 0.13 1. 2 0.11 0.1 to 0. 5 0. 25 to 0. 50 N11 0. 20 Nil 5. 7o 3. 40 0.13 1. 2 0.11 0.1 to 0. 5 0. 25 to 0. 50 Nil 0. 20 0. 011 7. 20 2. 80 0.15 1.2 0.11 0.1 to 0.5 0. 25 to 0. 50 0. 50 0. 50 N11 9.00 3.50 0.15 1. 2 0.11 0.1 to 0. 5 0. 25 to 0. 50 0. 50 0. 50 0. 020 6.15 3. 40 0.14 1. 2 0.11 0.1 to 0. 5 0. 00 to 0. 25 0. 50 1. 00 Nil 8.30 3. 00 0.14 1. 2 0.11 0.1 to 0. 5 0. 00 to 0. 25 0. 50 1.00 0. 014 7.50 3. 50 0.13 0. 5 0. 0s 0. 5 to 1. 5 0. 25 to 0. 50 0. 50 0.10 Nil 8.30 3. 80 0.13 0. 5 0. 08 0. 5 to 1. 5 0. 25 to 0. 50 0. 50 0.10 0.020 7.10 3.80 0.13 0. 5 0. 0s 0. 5 to 1. 5 0. 25 to 0. 50 0. 50 0.10 0. 070 3. 40 3.00 0.13 0. 5 0. 08 0. 5 to 1. 5 0. 25 to 0. 50 0. 50 0. 20 Nil 8.30 4.00 0.13 0.5 0. 08 0.50) 1.5 0.25 m 0.50 0. 50 0.20 0.080 2.10 3.40 0.15 0. 5 0.03 0. 5 to 1. 5 0. 25 to 0. 50 1. 00 0. 50 N11 5. 20 2.90 0.15 0. 5 0. 0s 0. 5 to 1. 5 0. 25 to 0. 50 1. 00 0. 50 0.020 4. 10 2. 30

vapours, such as carbon dioxide and Water vapour, par- An addition of beryllium to mild steels Within the ic l rly at g temperatures p p range specified above does not adversely affect the lures 111 legloll mechanical properties of the mild steel.

Accordlng to the 1nvent1on an amount of beryllium in w We claim the proportlon of fi-om 001% to 008% (pre r y A mild steel containing from 0.13 to 0.15% by weight to i' g g g nuld sgeel of carbon, from 0.5 to 1.2% by weight of manganese, g c g i i i g g 6 i 2 :22 s 6% from 0.08 to 0.11% by weight of silicon, from 0.014 to 0 Y g g 1 0.08% by Weight of beryllium, from 0.0 to 0.50% by 0.3% by weight of s1l1con, from O to 0.6% by weight ht f f O 0 t 107 b ht f l of copper, from 0 to 0.6% by Weight of molybdenum, W 0 copper mm 0 y i o m e from 0 to 1 by weight of nickel, from 0 to 1% b from 0.10 to 1.00% by we1ght of chronnum and trom weight of chromium and from 0 to 1.5% by Weight of "P 15% by wfilght 0f 0 0 1111131, the rema1mng aluminum, the remaining vconstituents f the mild steel constituents of the m1ld steel being 1ron and residuals. being iron and residuals.

The residuals are small quantities of elements such as References Cited In the file of thls Patent vanadium and cobalt which are inseparable completely from the melt during manufacture, which, as long as they do not exceed say 0.1% by weight each and are not added UNITED STATES PATENTS 2,382,466 Crafts Aug. 14, 1945 

